SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1c973886bc951e12fda11f5a336bbc1718ad9aa36db615f481c964c52a3cd55e' 
  AND token = 'grD19opcgt2SslX2UyzK172JQ7y+gIOOqu5084mgjTU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}